1. Field of the Invention
The present invention relates to a holder for holding a plurality of sensors in the form of combined signal transmitter-receivers. More particularly, the present invention relates to a rotatable sensor holder for holding a plurality of position sensors that are each aimed so that their respective axes are arranged at a different angle relative to each other.
2. Description of the Related Art
Rangefinding sensors generally emit a beam of light waves, sound waves, or radio waves that are reflected from a surface of an object to be sensed and are received and analyzed to determine the position of the object relative to the sensor. The effectiveness of such sensors is typically limited by beam reflection problems. Because a beam is reflected from a surface at an angle that is the same as the angle of incidence of the beam relative to the surface of the object to be sensed, if the surface of the object is so oriented that the incidence angle of the beam relative to the surface is too large, the beam can be reflected from the surface in a direction away from the sensor so that the sensor fails to receive the reflected beam, and consequently no determination of the position of the object can be made.
One way in which a single sensor has been positioned to detect objects spaced from the sensor is with the sensor supported for rotation about a vertical axis with the sensor aimed so that the beam emanates laterally, relative to the axis of rotation. However, if the surface of the object is sloped so that the tangent to the surface at the point of impact of the beam is not substantially perpendicular to the beam axis, the object will not be detected.
Another approach has been to provide a multiplicity of sensors around the outer perimeter of a cylindrical sensor holder. However, the same shortcoming exists as described above for the single sensor arrangement.
It is an object of the present invention to overcome the shortcomings of the above-described approaches to object sensing by reflected beams.
It is another object of the present invention to provide a sensor holder that orients a plurality of sensors so that beams emanating from the sensors can be received to detect objects having surfaces of varying angular orientations relative to the beam directions of the beams emanating from the sensors.